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Hussman RL-5 cases

Hi Guys,

so im new to this whole site and this is my first post. Im out of Ontario im a relatively new mechanic and my company has recently made a push into the supermarket refrig field, and ive already run into an issue that has seem to stump most people including hussman tech support.

Im getting ice build-up in the plenium of my case, and the ice will gradually build up until it stops the evaporator fan blades. But im getting a positive defrost off my coil, but the ice is not escaping the plenum and making its way to the trough at the front of my case.

These are refurbished freezer cases using 407A. im running them in a bank of 3 cases off a single sporlan EEPR valve, which is controlled by a einstein E2 controller. But my whole line-up is having the same issue.
The issue has been happening ever since construction was finished 6 months ago, and ive de-iced the coils 3 times since.

The cases have electric defost (3 daily at 55 mins. with a minimum of 40 mins.) I increased the defrost time and minimum to try and get more heat in the plenum. Ive verified with hussmans spec that all my heaters are in the exact place they should be. my superheat has been set. ive wedged up the plenum with washers but very minimal as to not affect the air flow when the fans are in refrig mode. i also have a slope to the front of my case so the water should be flowing to the drain.

My only guess at this point is that i have moisture between the bottom of the case and the isulation. Any ideas or has anyone seen this?

so frost is forming. then in defrost were making water out of that frost and it drops off the coil, it lands on the deck of the case, and should route to the drain right? Is the deck temperature above freezing during defrost. Sometimes it's not. This is why we have drain PAN heaters. is there on equipped and does it work? There must be one, and it must work. They must stay on the duration of defrost, and into DRIP TIME.

Now. Your thinking a failed insulation on the deck is the issue. If this was the case, the heat from the store, would be attempting to get into the case through that failed insulation, and the metal (skin) would be the vapor barrier, so the water would form on the exterior underside of the case if this were the case. If the structure has not been compromised, due to failed insulation, the condensate forming from frost should by gravity route to the drain of the case. Have you simulated this with a bucket of water. Is the case level?

Another thing to keep in keep in mind. If at one time there was a drain stoppage and the case iced up due to that, and the last 3 technicians who deiced the case did not clear the case entirely of the ice, this can also do this. You have to start from scratch. When encountering and iced up case, you have to completely deice.

so frost is forming. then in defrost were making water out of that frost and it drops off the coil, it lands on the deck of the case, and should route to the drain right? Is the deck temperature above freezing during defrost. Sometimes it's not. This is why we have drain PAN heaters. is there on equipped and does it work? There must be one, and it must work. They must stay on the duration of defrost, and into DRIP TIME.

There are only 3 heaters on these cases a front and rear coil heater and a trough heater. My case temperaature rises to about 50Fto60F during defrost. Yes the frost is being cleared off the coil and freezing on the way to the drain, but it doesnt ever make it out of the plenum, over time it seals the gap between the plenum and the deck and builds up to the fans.

The reason why i say the insulation is because through my searching for an answering i was told its possible to create ice between the metal skin and the insulation which could cause bubbling of the skin and hold pockets of water. im thinking the issue is not the insulation beneath the case but a possible broken seal from within the case that is allowing water beneath the skin.

i did completely cleared the case of ice and my slope is there, but i can still create more slope if need be by propping the back end up more. ive simulated it with a bucket of water, and it clears no problem but over time lets say a month when i got back the ice has formed again, and by 2 months its stopping fans.

im going back to site on monday and ill have to take a better look at the decks temperature during defrost but i know my case plenum temperature is about 32F.

The Klixon are working, but even when it terminated my control will not initiate refrigeration till 45mins pass. ive set my E2 control to show me when defrosts are being terminated early, and i find its only at night while they're restocking shelves. But ive set up my minimum defrost time to be what hussman recomends as the actual defrost time 40mins. i increased my defrost time to 55 mins.

this is the only location we take care of that we have this issue and since they are refurb cases im pretty sure it must be a seal or a structure issue.

i have 3 because originally it asked for 2 at 45 mins with a 30 minute minimum defrost. i figure if i added another i wont be removing as much frost off my coil and introducing as much water per defrost, and maybe i could help heat up the plenum and get rid of the risidual water that has not left the plenum from the previous defrost. i understand its not necessary but at this point im trying to rule everything out before pulling apart cases themselves or making adjustments to the slope on my whole line up.

When the case freezes up is the drain and trough still clear? If the drain is froze over too I would suggest looking at the drain trap and make sure it's not backwards or rotated at all by the installer. We also had a ton of faulty tees sent out by Hussmann that started to crack and crumble that they paid us to replace in entire stores that were still fairly new.